ratelimit

Documentation

Index

• type Clock
• type Config
• type Limiter
  • func New(cfg Config, rate int, rep func(Config, int64), opts ...Option) Limiter
• type Option
  • func Per(per time.Duration) Option
  • func WithClock(clock Clock) Option
  • func WithSlack(slack int) Option

Types

type Clock

type Clock interface {
	Now() time.Time
	Sleep(time.Duration)
}

Clock is the minimum necessary interface to instantiate a rate limiter with a clock or mock clock, compatible with clocks created using github.com/andres-erbsen/clock.

type Config

type Config struct {
	ID      string
	Alias   string
	Type    string
	Max     float64
	Current int64
}

type Limiter

type Limiter interface {
	// Take should block to make sure that the RPS is met.
	Take() time.Time
	FixedTake()
	Current() int64
	Done()
}

Limiter is used to rate-limit some process, possibly across goroutines. The process is expected to call Take() before every iteration, which may block to throttle the goroutine.

func New

func New(cfg Config, rate int, rep func(Config, int64), opts ...Option) Limiter

New returns a Limiter that will limit to the given RPS.

type Option

type Option interface {
	// contains filtered or unexported methods
}

Option configures a Limiter.

var WithoutSlack Option = slackOption(0)

WithoutSlack configures the limiter to be strict and not to accumulate previously "unspent" requests for future bursts of traffic.

func Per

func Per(per time.Duration) Option

Per allows configuring limits for different time windows.

The default window is one second, so New(100) produces a one hundred per second (100 Hz) rate limiter.

New(2, Per(60*time.Second)) creates a 2 per minute rate limiter.

func WithClock

func WithClock(clock Clock) Option

WithClock returns an option for ratelimit.New that provides an alternate Clock implementation, typically a mock Clock for testing.

func WithSlack

func WithSlack(slack int) Option

WithSlack configures custom slack. Slack allows the limiter to accumulate "unspent" requests for future bursts of traffic.